Asthma Asthma

DR Sattam AleneziEM consultant

Asthma is one of the most common chronic diseases in adults

Affecting 300 million people worldwide

PATHOPHYSIOLOGYPATHOPHYSIOLOGY

- a chronic inflammatory disorder that is characterized by :

Bronchial hyper responsiveness Airway obstruction

Bronchospasm:Bronchospasm:

Is triggered by allergens or other stimuli.

Mast cells are activated through immunoglobulin E receptors to release inflammatory mediators that directly target bronchial smooth muscle.

Inflammation is central to the pathophysiology of asthma, and can lead to permanent changes in airway structure and pulmonary function, in a process known as airway remodelling

Inflammatory cells involved Inflammatory cells involved in asthmain asthma Lymphocytes.Mast cells.Eosinophils.Neutrophils.Dendritic cells. Macrophages.Epithelial cells

Mechanism of airway obstruction in severe asthma

HISTORY AND PHYSICAL HISTORY AND PHYSICAL EXAMINATIONEXAMINATIONChronic cough. Wheeze.Dyspnea.

patients often present with only 1 of these symptoms, which can make diagnosis challenging.

Symptoms of asthma are typically worse at night or early in the morning.

A personal history of atopy and family history of asthma favor the diagnosis.

Common precipitantsCommon precipitants House dust mites. Animal dander. Cockroaches.Alternaria. Pollens, and molds. Air pollutants and sulfites can

cause exacerbations

In a recent multicenter study of 654 asthmatics, exposure to environmental tobacco smoke was associated with worse lung function, higher acuity of exacerbations, and increased health care use.

Viral respiratory infections.Aspirin and other NSAIDs.Occupational exposure to

chemicals and dust.Strong emotional expressionExercise. Menstrual cycles .

Risk factors for severe, Risk factors for severe, uncontrolled asthmauncontrolled asthmaPrevious intubations or intensive

care admissions. 2 or more hospitalizations for

asthma in the past year. 3 or more ED visits for asthma in

the past year. Hospitalization or ED visit for

asthma in the past month.Using more than 2 canisters of

short-acting b-agonist monthly

Co morbidities that could Co morbidities that could aggravate asthmaaggravate asthma

Allergic bronchopulmonary aspergillosis,

Gastroesophageal reflux disease. Obesity. Rhinosinusitis. Obstructive sleep apnea.Depression.

Asthma in eldelry :Asthma in eldelry : Underdiagnosed and

undertreated .Is more likely to have reduced

perception of bronchoconstriction. Older adults are more likely to

have comorbidities or use medications (eg, b-blockers, acetylsalicylic acid, NSAIDs) that may exacerbate asthma.

Mild asthma:Mild asthma:PEF 70% of predicted. Dyspnea on exertion and

increased respiratory rate. They are able to speak in

sentences and to lie down. Moderate wheeze may be heard

on auscultation.

Moderate asthma:Moderate asthma:PEF 40%–69%.Dyspnea at rest.More comfortable sitting than

lying down. Loud wheeze is commonly heard

throughout exhalation. Suprasternal retractions and use

of accessory respiratory muscles are commonly seen.

Severe asthma:Severe asthma:PEF <40%. Use of accessory respiratory

muscles Inability to speak or lie supine

because of dyspnea.Pulsus paradoxus Respiratory rate is often more than

30 breaths per minute. The patient is most comfortable sitting up and can be agitated.

Loud wheeze is heard throughout inspiration and expiration.

Cyanosis, decreasing level of consciousness, and respiratory muscle fatigue are markers of impending respiratory arrest. .

DIFFERENTIAL DIAGNOSISDIFFERENTIAL DIAGNOSIS

“all that wheezes is not asthma; all that wheezes is not obstruction.”

Asthma ?

Upper airway obstruction ?

Congestive heart failure ?

COPD exacerbate ?

. Diagnosis

Asthma COPD Congestive heart failure Pulmonary embolism Pneumonia Tumors Cough secondary to drugs (eg, angiotensin-

converting enzyme [ACE] inhibitors) Foreign body in trachea or bronchus Aspiration pneumonitis Allergic rhinitis and sinusitis Postnasal drip Gastroesophageal reflux Vocal cord dysfunction Recurrent cough not caused by asthma

WHAT INVESTIGATIONS YOU WHAT INVESTIGATIONS YOU DODO

ELECCBC

CXR

SPO2

ABG

ECG

PEFR

PEF:PEF: Is the most commonly used test in the ED

to assess the degree of obstruction. PEF readings are safe, quick, and cost-

effective. They can be used to monitor a patient’s

response to treatment over time. Normal PEF values vary with gender,

height, age, and ethnicity. A value less than 200 L/min usually

indicates severe obstruction. Repeated PEF or FEV1 measurements at

ED presentation and 1 hour after treatment are the strongest predictors of hospitalization .

Chest radiographsChest radiographsare generally not useful commonly show pulmonary

hyperinflation.They should only be used to

evaluate other suspected causes of the patient’s symptoms (eg, pneumonia, pneumothorax, congestive heart failure).

Electrocardiograms should be done in patients with suspected cardiac disorders.

Pulse oximetry is a reliable way to monitor for hypoxemia in the asthmatic patient.

It is recommended for patients in severe distress, PEF or FEV1 less than 40% of normal, or if the patient cannot perform lung function measurements.

Arterial blood gasArterial blood gas

Rarely done, and are indicated only in patients with PEF less than 25% of predicted, because this group alone is at risk for significant hypercapnia or acidosis.

Increased or normal arterial carbon dioxide pressure (PaCO2) is a worrisome sign.

The serum potassium concentration should be measured, particularly in patients with prior corticosteroid or diuretic treatment.

TREATMENTTREATMENTABC .Full set of vital signs.O2sat RRRespiratory effort.

Start treatment.

Aim of treatment :Aim of treatment :

Correct hypoxia.Rapid reversal of airway

obstruction.Treat inflammation

Give O2 Bronchodilators .Steroids.

Bronchodilators: Bronchodilators:

B-agonist .Anticholinergics.Mg.

b2-AGONISTSb2-AGONISTSPotent bronchodilators that act on b

receptors to quickly and effectively relax bronchial smooth muscle.

Short-acting b-agonists are the recommended first-line therapy for the acute asthma exacerbation.

Albuterol is the most commonly used b2-agonist for acute asthma.

b2-Agonistsb2-AgonistsMultiple forms, including MDI,

nebulizer, subcutaneous injection, and intravenous injection.

Aerosolized bronchodilators have been administered by continuous-flow nebulization.

Multiple studies have found little difference in efficacy between MDI and nebulizer therapy.

For acute asthma, 2 to 6 inhalations of albuterol are given with MDI and spacer device.

Therapy is repeated every 20 minutes for up to 4 hours until there is maximal improvement in respiratory symptoms.

2.5 to 5.0 mg of nebulized albuterol is given every 20 minutes to a total of 3 doses (maximum of 15 mg in one hour).

Albuterol can also be given as a continuous nebulization at a rate of 10 to 15 mg over 1 hour.

Non selective Beta agonist that requires (IV/sub cut) admin.

Effective bronchial smooth muscle dilator with rapid onset of action.

Use for very severe and life threatening asthma.

“If you hesitate to give epinephrine to a severely distressed asthmatic, you should consider the fact that if the patient deteriorates further and suffers cardiorespiratory arrest the first drug you will administer is epinephrine 1mg IV”

What about Adrenalin?What about Adrenalin?

Subcutaneous epinephrineSubcutaneous epinephrine

0.01 mg/kg to maximum dose of 0.3–0.5 mg ,

OR nebulized epinephrine can be considered.

ANTICHOLINERGICSANTICHOLINERGICSBlock the action of acetylcholine

on the parasympathetic autonomic system.

They decrease vagally mediated smooth muscle contraction in the airways

In combination with short-acting b-agonists

Ipratropium bromide is the most commonly

Ipratropium has a slow onset of action, reaching its peak effect in 90 minutes.

0.5 mg of Ipratropium is given by nebulization every 20 minutes for 3 doses.

Alternatively,8 puffs with MDI and spacer can be given every 20 minutes for up to 3 hours.

MAGNESIUM SULFATEMAGNESIUM SULFATEThere is evidence that magnesium

inhibits the influx of calcium into smooth muscle cells, causing bronchodilatation

Magnesium acts on neutrophils to decrease inflammation

For life-threatening exacerbations of acute asthma, or if the exacerbation remains severe (PEF <40%) after 1 hour of conventional therapy.20

CORTICOSTEROIDSCORTICOSTEROIDS

The most potent and effective anti-inflammatory agents available for the treatment of asthma.

Their onset of action can take up to 6 hours to become clinically apparent.

Systemic corticosteroids come in multiple forms, including oral, intravenous, and intramuscular.

The efficacy of oral corticosteroids is equivalent to the intravenous form. Oral steroids are preferred, because they are less invasive.

Prednisone is administered orally at a dose of 40 to 60 mg.

METHYLXANTHINESMETHYLXANTHINES

Currently, the methylxanthines are not recommended as therapy for the acute exacerbation of asthma.

KetamineKetamineIs a dissociative agent that dilates

bronchial smooth muscle and increases circulating catecholamines.

Ketamine reduces bronchospasm and can help delay the need for intubation.

Several case reports of patients with status asthmaticus treated with intravenous Ketamine have shown promising results.

In these studies, Ketamine was given as an intravenous bolus of 0.5 to 1 mg/kg, then as an infusion of 0.5 to 2 mg/kg over 1 hour.

NONINVASIVE VENTILATIONNONINVASIVE VENTILATION

Support and reduce the patient’s respiratory effort, giving enough time to allow other treatments to take effect and possibly avoid intubation

INTUBATION AND INTUBATION AND MECHANICAL VENTILATIONMECHANICAL VENTILATIONRisk factors for death from asthma previous intubations or intensive

care admissions, or recent history of poorly controlled asthma

4% of patients hospitalized for asthma require endotracheal intubation and mechanical ventilation.

Mortality among those requiring ventilation is around 8%.

Death can be caused by severe obstruction, extreme hyperinflation, complications of acute asthma, failure by the patient or clinician to appreciate the severity of the disease, and failure to optimally control asthma.

There is no evidence to support a specific pH or PCO2 for intubation, and the decision should be made on clinical grounds.

Intubation should be done by the most experienced clinician available,

Ideally with a large-bore endotracheal tube (8.0 mm).

Rapid sequence intubation (RSI) is the preferred approach, because the patient is typically exhausted with little physiologic reserve.

KetamineKetamineis the induction agent of choice for

sedation and intubation of an asthmatic

Intravenous Ketamine is given at a dose of 1 to 2 mg/kg at a rate of 0.5 mg/kg/min and results in general anesthesia without respiratory depression.

Propofol induces bronchodilatation and is an alternative induction agent, but can cause hypotension.

Respiratory rate settings should be

decreased to give the patient more time to exhale.

Initial tidal volume should be set at less than 8 mL/kg, to decrease the risk of lung inflation.

Bronchodilators and systemic corticosteroids can be administered to the ventilated patient.

For the intubated patient with refractory asthma, intravenous ketamine or inhaled isoflurane can be useful adjuncts.

Heliox can also be considered.

ASTHMA AND PREGNANCYASTHMA AND PREGNANCYSABAs, anticholinergics, and

inhaled corticosteroids seem to be safe during pregnancy.

Budesonide is the long treatment of choice, because it has been extensively studied in pregnancy

Systemic corticosteroidsSystemic corticosteroidsHave been linked with

prematurity,low birth weight, preeclampsia,

congenital malformations, and cerebral palsy.

Should be used with caution.

A meta-analysis of mothers treated with oral corticosteroids in the first trimester showed a significant increase in the risk of oral clefts in their offspring.

A recent large-scale study of antenatal steroids showed no difference in body size or survival free of major neurosensory disability in children at

2 years of age.

Epinephrine should be avoided during pregnancy, except in cases of anaphylaxis.

Warning signs that a patient Warning signs that a patient will need intubationwill need intubationDecreasing level of

consciousness,Cyanosis, Deterioration of FEV1 or PEF, Inability to maintain

oxygenationby mask, Respiratory muscle fatigue,Cardiac instability.

DISPOSITIONDISPOSITIONB-Agonists and corticosteroids

should be included in the discharge plan

A short course of corticosteroids

Patients with FEV1 or PEF less than 40% should be admitted to the intensive care unit.

Adjunctive therapies and mechanical ventilation should be considered for these patients.

Patients who continue to have features of severe exacerbation after initial treatment require admission.

Patients who show greater than 75% PEF following one hour of initial treatment are suitable candidates for discharge from the ED.

SUMMARYSUMMARY

Asthma is a chronic inflammatory disease that is commonly encountered in the ED.

Early signs of worsening asthma should be recognized and immediate treatment

b-Agonists, anticholinergics, and corticosteroids are mainstays of treatment

Magnesium sulfate, epinephrine, and heliox can be used .

Considered for life-threatening presentations of asthma.

Control of environmental triggers, improvements in daily maintenance therapy for asthma, and increasing patient education should help to reduce the severity and frequency of asthma exacerbations seen in the ED.

Thank you